The purpose of the bore holes is to produce uniform bridges between the bore holes. These are counted by a sensor and converted into data about the angular position of the flywheel, and hence of the crankshaft. For this it is of course necessary for the angular position of the flywheel relative to the crankshaft to be definitely fixed.
Flywheels of this kind are in use in large numbers, but have the disadvantage that as a result of the arrangement of bore holes at the circumference of the disk and the material remaining between the bore holes, also in cooperation with the sensor, noises which are characterised as a siren-effect occur, mostly within specific engine speed ranges, dependent on the particular design. Such noises are very annoying and can impair the comfort of occupants of the vehicle when an internal combustion engine with such a flywheel is used.
Means for damping this phenomenon are costly, and moreover do not have the desired technical effect.